By Udita Shukla
For a planet to be habitable, one of the most significant prerequisites is the presence of a liquid which should serve as a medium for life-supporting chemical reactions to take place and the most obvious choice is water. Other life essentials are molecules as the basic building blocks of life (for instance, the phosphorus in our DNA), and an energy source. As it turns out, not all planets that can support life will have to be identical twins to our Earth. In order to find planets, we need to anticipate their chemical composition, atmospheric profiles, among other things, so we can build instruments accurate and powerful enough to detect and study them. This is known as planet-modelling.
Putting exoplanets to use
Scientists at the University of Washington, Seattle, are working on creating three-dimensional models of planets at different distances from stars. The so-called Virtual Planet Laboratory allows researchers to simulate what planets would look like from space, and what their environment would be like before they are actually discovered in the universe. Stars are given a certain spectral type. Subsequently, the virtual planet software recreates atmospheric and geographic conditions. The vegetation, soil and temperatures also take on different forms as the spectral type of the host star and the intervention (separation) distances vary. Many exoplanets have been spotted so far. According to NASA statistics, from 1996 to 2014, nearly eight hundred planets have been discovered.
The mysterious TrES-2b
Nicknamed as the Dracula Planet, TrES-2bs atmosphere possesses a reflective capacity lesser than that of coal. Data modelling suggests it reflects less than one per cent of the light incident upon it. Due to this, its atmosphere is very dark. As per David Kipping, an astronomer at the Harvard-Smithsonian Centre for Astrophysics, It’s darker than the blackest lump of coal; than dark acrylic paint you might paint with. It’s bizarre how this huge planet became so absorbent of all the light that hits it.
Moreover, its temperature is around 980 degrees Celsius, comparable to that of the hot lava on earth. These properties couple to give it a spooky bright, red glow. TrES-2b orbits a star named GSC 03549-02811, located 750 light years away from the solar system towards the direction of the constellation, Draco. By calculating its mass and radius, astronomers have been able to determine its bulk composition which seems similar to that of the gas giant, Jupiter.
OGLE-2005-BLG-390Lb
Known as the Hoth, the planet affords a deathly chill of negative 220 degree Celsius. Some astronomers claim that it may support temperature conditions and the chemical composition essential for life to exist. The extremely cold temperature suggests the existence of frozen states of substances (which are normally found in liquid or gaseous states on Earth) like, water, ammonia, methane, nitrogen. This is possible only if the planet has a rocky surface. Hoth orbits the star OGLE-2005-BLG-390L, about three thousand light years away from the earth, near the centre of the Milky Way. One of the most striking characteristics of the planet is its small size compared to the distance from its host star. It might very well be the smallest planet orbiting a star outside the solar system.
55 Cancri e: Burning hot
The planet orbits a Sun-like star, 55 Cancri A. It is about 8.63 times massive than the earth and nearly twice in diameter. Hence, it is also referred to as the super-Earth. The temperature prevalent on the side of the planet bearing the stars heat can reach up to 1.700 degree Celsius, which is hot enough to melt iron. Strangely, the hottest spot on the planet is not on the side that faces the stellar surface but is offset by nearly forty degrees to the east. This planet is made up of precious metals. Primarily, it is composed of carbon, which is also the chief reason for it to be a mine of high-worth metals.
The search continues
The search for exoplanets is largely driven by commercial outfits like SpaceX that intend to transport people to Mars by 2024. Moreover, a recent study claims that the Martian atmosphere contains 96 per cent carbon dioxide, which can be used to disintegrate (carbon dioxide) molecules into oxygen. Also, we have already been able to unravel many Saturnian secrets through Cassini while Juno is still out there orbiting Jupiter, tasting its atmospheric chemicals and other electromagnetic phenomena (like auroras). Summarily, it is hard to predict when we might stumble upon an earthly sibling! Till then, it seems as if the universe is not done rolling out its basket of surprises yet!
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